JP2001057219A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell with high characteristics by reducing partial distribution of reaction. SOLUTION: This fuel cell uses a laminated body sequentially laminated with single cells sandwiching an electrolyte film between a fuel electrode and an oxidizer electrode through a separator 40. The separator 40 is provided with a plurality of parallel fuel passages and a plurality of parallel oxidizer passage 33. In at lest the oxidizer passage, a plurality of parallel passage groups consisting of a plurality of parallel passages turn back and run in divided regions α-δ on a main surface of the separator plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell for generating electric power by utilizing an electrochemical reaction, for example, used in an electric vehicle or the like. Hereinafter, although the present specification particularly describes a polymer electrolyte fuel cell, the present invention can also be applied to a phosphoric acid fuel cell.

[0002]

2. Description of the Related Art As is well known, a fuel cell has a pair of electrodes via an electrolyte, a fuel is supplied to one of the electrodes, and an oxidant is supplied to the other electrode. This is a device that directly converts chemical energy into electric energy by electrochemical reaction. There are several types of fuel cells depending on the type of electrolyte. In recent years, a polymer electrolyte fuel cell using a solid polymer electrolyte membrane as an electrolyte has attracted attention as a fuel cell capable of obtaining high output. For example, when hydrogen gas is supplied to the fuel electrode and oxygen gas is supplied to the oxidant electrode, and current is taken out from an external circuit, reactions represented by the following chemical reaction formulas (1) and (2) occur. Cathodic reaction: H ₂ → 2H ⁺ + 2e ⁻ (1) Anodic reaction: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)

When this reaction occurs, hydrogen becomes a proton on the fuel electrode, moves with the water through the electrolyte to the oxidant electrode, and reacts with oxygen on the oxidant electrode to produce water. Therefore, the operation of the fuel cell as described above requires the supply and discharge of the reaction gas and the extraction of the current.

A separator plate for extracting current from a fuel cell and for efficiently flowing gas and water is disclosed in, for example, JP-A-58-161270 and JP-A-58-1612.
No. 69 and JP-A-3-206676. FIG. 6 is a cross-sectional view for explaining a conceptual configuration of a unit cell in the fuel cell disclosed in Japanese Patent Laid-Open Publication No. Hei 3-206763. In FIG. Is an oxidant electrode, 4 is a fuel electrode,
Reference numeral 5 denotes an electrolyte using a proton conductive solid polymer, for example, the electrolyte 5, the oxidant electrode 3, and the fuel electrode 4.
Constitutes the single cell 6.

FIG. 7 is an explanatory view showing the upper surface of the separator plate in the fuel cell shown in FIG. 6, and will be described with reference to FIG. That is, reference numeral 20 denotes a main surface of the separator plate 1, reference numeral 21 denotes an electrode supporting portion for supporting the electrode 3 in the separator plate 1, reference numeral 22 denotes an oxidant supply port formed in the separator plate 1 and supplies air as an oxidant, and reference numeral 23 denotes air. An oxidant discharge port for discharging the fuel, 24 is a fuel supply port for supplying fuel, and 25 is a fuel discharge port for discharging fuel. In the separator plates 1 and 2, the oxidant flow path 10 and the fuel flow path 11 are respectively formed by the grooves formed by cutting the main surface 20 and the space surrounded by the electrodes 3 and 4.

Hereinafter, the operation of the fuel cell will be described with reference to FIGS. 6 and 7. Oxygen gas supplied from the oxidant supply port 22 of the separator plate 1 is supplied to the oxidant electrode 3 through a plurality of oxidant passages 10 running in parallel, while hydrogen gas is supplied in the same manner as the oxidant. And the fuel gas flow path 1
1 to the fuel electrode 4. At this time, since the oxidant electrode 3 and the fuel electrode 4 are electrically connected outside,
The reaction of the chemical reaction formula (2) occurs on the oxidant electrode 3 side, and the unreacted gas and water are discharged to the oxidant discharge port 23 through the oxidant gas flow path 10. At this time, the fuel electrode 4
On the side, the reaction of the chemical reaction formula (1) occurs, and the unreacted gas is similarly discharged from the fuel outlet 25 through the fuel gas passage 11. The electrons obtained by this reaction flow from the electrodes 3 and 4 via the electrode supporting portions 21 and the separator plates 1 and 2.

As shown in FIG. 7, the oxidizing agent channel 10 has a bellows-shaped cross section on one surface of the separator plate 1, and has a plurality of parallel grooves. Also, the fuel gas passage 11 has a plurality of grooves similarly to the oxidant passage 10. In the above fuel cell, the gas flow path is increased by making the gas flow path longer by making a bellows type, thereby increasing the gas flow rate and thinning the film, thereby promoting the diffusion of gas necessary for the reaction and generating the gas at the oxidant electrode. It discharges water efficiently.

Further, as shown in FIG. 8 which is a perspective view of a separator plate disclosed in Japanese Patent Application Laid-Open No. 62-40169, a device has been devised in which a region is completely divided to form a bellows channel. In the figure, 7 is a gas separation plate, 8, 8a are grooves, 9,
9a is a rib. In this method, the inlet and the outlet of one fluid occupy almost the entire area of one side length of the separator plate, and there is a disadvantage that it is difficult to connect other fluids.

[0009] Further, as shown in FIG. 9 which is a perspective view of a separator plate shown in WO96 / 20510, a flow path in which a parallel flow path is simply folded is also considered. In the figure, 71 is an air flow path, 72 is a fuel supply port, 73 is an air supply port, 74 is an air discharge port, and 75 is a fuel discharge port.

[0010]

However, in the above-mentioned conventional separator plate, the reaction is promoted in a region where the concentration of the fluid flowing through the flow path is high, and the current density increases in that region, and the current density is biased. However, no consideration has been given to the bias of the current density, and there has been a problem that the bias of the reaction causes a substantial reduction in the reaction area, thereby deteriorating the characteristics.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a fuel cell capable of reducing bias in reaction distribution and obtaining high characteristics.

[0012]

A first fuel cell according to the present invention comprises a single cell having an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode, and a fuel cell for supplying a fuel fluid to the fuel electrode. A plurality of fuel flow paths parallel from the fluid supply port to the fluid discharge port and a plurality of oxidant flow paths parallel from the fluid supply port to the fluid discharge port for supplying an oxidant fluid to the oxidant electrode are provided. In a fuel cell comprising a laminated body in which separator plates are sequentially laminated, at least the plurality of oxidant flow paths are formed of a plurality of groups of parallel flow paths, and the plurality of groups of parallel flow paths are the main flow paths of the separator plate. The vehicle travels while turning over each of the divided areas on the surface.

A second fuel cell according to the present invention comprises a single cell having an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode;
A plurality of fuel flow paths in parallel from a fluid supply port to a fluid discharge port to supply a fuel fluid to the fuel electrode and a fluid supply port to a fluid discharge port to supply an oxidant fluid to the oxidant electrode. A separator plate having a plurality of parallel oxidant flow paths, and in a fuel cell composed of a laminated body sequentially laminated, at least the plurality of oxidant flow paths are composed of a plurality of parallel flow paths, the plurality of groups of The points of the parallel flow paths, which are at the same distance from the respective fluid supply ports, are dispersed and arranged on the main surface of the separator plate.

The third fuel cell according to the present invention includes the first fuel cell described above.
In the fuel cell, the separator plate circulates a cooling medium and includes a plurality of parallel coolant channels, and the plurality of coolant channels include a plurality of groups of parallel channels, and the plurality of groups of parallel channels. The road travels by turning over a region where the divided region where the oxidant flow path travels is projected on the separator plate.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 The fuel cell of the present embodiment uses a stacked body in which single cells each having an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode are sequentially stacked via a separator plate. The separator plate has a plurality of parallel fuel flow paths for supplying a fuel fluid to the fuel electrode from a fluid supply port to a fluid discharge port, and a plurality of parallel oxidant flows for supplying an oxidant fluid to the oxidant electrode. A passage is provided from the fluid supply port to the fluid discharge port.For example, the fuel passage is provided on one surface of the separator plate, the oxidant passage is provided on the other surface of the separator plate, or each passage is provided as a separate separator. Provided on a board.

In the separator plate, at least the plurality of oxidizing agent channels are not meandered as a group of parallel channels, but are divided into a plurality of groups each including a plurality of parallel channels. The vehicle travels while turning over each of the divided areas on the main surface of the plate. In other words, by arranging the points at the same distance from the respective fluid inlets of the plurality of groups of parallel flow paths, that is, regions having the same reaction amount at the same fluid concentration, by dispersing them on the main surface of the separator plate, It is intended to disperse the reaction.

FIG. 4 is a cross-sectional view of the fuel cell stack according to the first embodiment of the present invention. In FIG. 4, reference numeral 6 denotes a single cell, and 39 denotes a fuel channel and a coolant channel provided on each surface. Separator plate, 40 is a separator plate provided with an oxidant flow path, 33 is an oxidant flow path,
43 is a fuel passage, and 53 is a coolant passage.

FIG. 1, FIG. 2 and FIG. 3 are plan views showing a fuel flow path surface, for example, an oxidizing flow path surface and a cooling flow path surface for flowing air, respectively, of the separator plate used in the fuel cell. FIG. 3 showing the road surface is the back surface of the separator plate provided with the fuel flow path surface shown in FIG. In the figure, 26 is a fuel supply port, 27 is a fuel discharge port, 41 is a main surface on the fuel flow path side,
Reference numeral 42 denotes an electrode support that comes into contact with the anode electrode surface;
Is a parallel fuel flow path, 45 is a hole through the shaft, 4
6 is a fluid confluence, 24 is an oxidant supply port, 25 is an oxidant discharge port, 31 is an oxidant flow path side main surface, 32 is an electrode support, 33a to r are parallel oxidant flow paths, and 28 is cooling. The agent supply port, 29 is a coolant discharge port, 51 is a main surface of the coolant channel side, and 53a to j are parallel coolant channels.

Next, this embodiment will be specifically described.
As shown in FIGS. 1 to 4, in the present embodiment, a separator plate 39 having a fuel passage on one surface and a coolant passage on the other surface and a separator having an oxidant passage surface through which air flows, for example. The fuel cell was constructed by sequentially laminating the plate 40 and the single cell 6. The electrode support is horizontal 20cm, vertical 11c
The supply port and the discharge port of each flow path are provided on the side end side of the electrode support portion in a rectangular shape of m. Further, a hole 45 penetrating the fastening shaft at two places and a fuel junction 46 are arranged in the electrode portion.

Each of the flow paths is a groove formed by, for example, shaving the surface of a separator plate. The fuel flow path divides a region p from the fuel supply port 26 to the junction 46 into nine parallel flow paths 43a to 43a. i meander together and run (shaft 45
), And from the junction 46 to the outlet 27
The parallel flow paths 43j to 43 in which the number q is reduced to ま で of the three regions q are meandering (FIG. 1).

In the oxidant flow path, 18 parallel flow paths 33a to 33r run from the oxidant supply port 24 to the discharge port 25.
The electrode support is positioned at the shaft center line and the electrode support center line.
Four (43a-d), five (43e-i), five (43)
j to n), a plurality of groups of parallel flow paths branched into four lines (43 to r) meanderingly flow (FIG. 2).

In the coolant passage, ten parallel passages 53a to 53j run from the coolant supply port 27 to the discharge port 28.
Two (53a, b), three (53c-e), three (53f-)
h) A plurality of groups of parallel flow paths branched into two (53i, j) meander (FIG. 3).

The operation will be described. On the fuel flow path side,
The grooves 43a to 43i are connected to the grooves 33a to 33o of the electrode section up to the junction 46.
Is flowing together in the region p except for a part of the branch of the shaft portion, and the three flow passages 43j to l run together in the region q after the junction 46. Even when, for example, 43c is closed, the current distribution in the region p is covered by the electrode portions that are in the jurisdiction of the adjacent flow paths 43b and 43d, and the current is not biased in the region.

On the other hand, the oxidant supply port 2
4 to supply port 24 to oxidant discharge port 25
The current density in the upstream portion up to / 3 is about 20% higher than the current density in the downstream portion (results separately measured by a test device in which a single cell is connected), but in this embodiment, the upstream portion has a current density of 4%. Since the current density is dispersed in two regions, the bias of the current density is reduced, and the cell voltage at the current density of 500 mA / cm ² is improved by 10 mV as compared with the case where the division is not performed.

Further, when laminated as shown in FIG.
In the same manner as described above, the coolant flow channel regions α to δ are provided in the separator plate 39 so as to correspond to the oxidant flow channel regions α to δ formed as described above.
In this case, since the coolant flow path also flows through the divided area in the same manner as the oxidant flow path, a portion where heat is concentrated is effectively cooled, the temperature deviation in the plane is reduced by 2 ° C., and the cell resistance is reduced. 10
mΩcm ² was reduced, and the characteristics were further improved by 7 mV.

As described above, in this embodiment, each flow path covers the entire electrode surface, so that even if any of the parallel flow paths is closed, the movement of the current distribution does not cover the entire surface. And complement each other almost uniformly. Further, the region where the current density becomes large is dispersed along the divided region of the oxidant flow path.
Also, since the coolant channel is also divided like the oxidant channel. Cooling can be performed along the region that generates heat due to the electrode reaction. That is, in the present embodiment, the heat generation region is dispersed in the oxidant flow path region divided by the vertical line, and the cooling region is also dispersed in the same region, so that the portion where heat is concentrated is effectively cooled, so that the in-plane The temperature bias was reduced, the cell resistance was also reduced, and the effect of improving the characteristics was obtained.

Further, in the present embodiment, since the junction 46 is provided in the fuel flow path, a part of the flow path is closed, and the fuel having a low hydrogen concentration immediately before the junction is supplied to the junction 46. By merging with the fuel of the other separator plate, the hydrogen concentration was averaged again, and in the region q downstream of the merging portion, the current distribution was almost the same as that of the other stacked portions.

In the present embodiment, the case where a separator plate having a coolant flow path through which a cooling medium flows is described, but the use of a separator plate having a coolant flow path is limited. is not.

Although the present embodiment is formed of a thermoplastic resin containing carbon, a similar improvement in moldability can be expected with a thermosetting resin such as a phenol resin.

Embodiment 2 FIG. FIG. 5 is a plan view of a surface 31 of the separator plate according to the second embodiment of the present invention, on which an oxidizing agent channel is provided. The electrode supporting portion is a rectangle having a size of 20 cm in the horizontal direction and 11 cm in the vertical direction as in the first embodiment, and the supply port and the discharge port of each flow path are provided on the side end side of the electrode supporting portion. There is no through hole inside. The oxidant flow path has 16 parallel flow paths 33a to 33p running from the oxidant supply port 24 to the discharge port 25, and has four regions α, β, γ, and δ obtained by dividing the electrode support portion by horizontal lines. Branch one by one (33a-d, 33e-h, 33i-l, 33m-p)
The plurality of groups of parallel flow paths meanderingly flow. Although fuel flow grooves are not shown, in FIG. 1, eight grooves running parallel to the whole area from the fuel supply port 26 to the discharge port 27 meander. Although the coolant channel is not shown, in FIG. 3, twelve parallel channels run from the coolant supply port 28 to the discharge port 29, and four regions α, β, and γ that are almost the same as the oxidant channel. , Δ branching into three streams each.

The operation is almost the same as that of the first embodiment. However, in this embodiment, the heat generation region is dispersed in the oxidizing agent flow path region divided by the horizontal line, and the cooling region is also dispersed in the similar region. By effectively cooling the portion where heat is concentrated, the unevenness of temperature in the plane is reduced, and the cell resistance is also reduced, thereby improving the characteristics.

In the above embodiment, the flow path meanders while turning over each area of the separator plate. The reaction distribution state can be appropriately adjusted by adjusting the direction of the meandering.

[0033]

According to the first fuel cell of the present invention, a single cell in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode, and a fluid supply port for supplying a fuel fluid to the fuel electrode, A plurality of fuel flow paths parallel to the discharge port and a separator plate having a plurality of oxidant flow paths parallel to the fluid discharge port to supply the oxidant fluid to the oxidant electrode, In a fuel cell comprising a laminated body sequentially laminated, at least the plurality of oxidant flow paths are formed of a plurality of groups of parallel flow paths, and the plurality of groups of parallel flow paths are divided on the main surface of the separator plate. Since the vehicle travels while turning over the regions, there is an effect that the bias of the reaction distribution is small and high characteristics can be obtained.

The second fuel cell of the present invention comprises a single cell having an electrolyte membrane sandwiched between a fuel electrode and an oxidizing electrode, and a fluid supply port for supplying a fuel fluid to the fuel electrode. And a separator plate having a plurality of oxidant flow paths parallel to each other from a fluid supply port to a fluid discharge port for supplying an oxidant fluid to the oxidant electrode. In a fuel cell comprising a stacked body, at least the plurality of oxidant flow paths are formed of a plurality of groups of parallel flow paths, and each of the plurality of groups of parallel flow paths at the same distance from each fluid supply port. Are dispersedly arranged on the main surface of the separator plate, and there is an effect that the bias of the reaction distribution is small and high characteristics can be obtained.

In a third fuel cell according to the present invention, in the first fuel cell, the separator plate is provided with a plurality of parallel coolant passages through which the cooling medium flows, and the plurality of coolant passages are provided in parallel. The plurality of groups of parallel flow paths, the plurality of groups of parallel flow paths, the divided area where the oxidant flow path travels is projected on the separator plate, the area is turned back, and travels in the plane. There is an effect that the temperature deviation is reduced, the cell resistance is reduced, and the characteristics are improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a fuel passage surface of a separator plate according to a first embodiment of the present invention.

FIG. 2 is a plan view of an oxidant flow path surface of the separator plate according to the first embodiment of the present invention.

FIG. 3 is a plan view of a coolant channel surface of the separator plate according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of the stack according to the fuel cell of the first embodiment of the present invention.

FIG. 5 is a plan view of an oxidant flow path surface of a separator plate according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view for explaining a conceptual configuration of a unit cell in a conventional fuel cell.

FIG. 7 is an explanatory view showing an upper surface of a separator plate in a conventional fuel cell.

FIG. 8 is a perspective view showing a configuration of a conventional separator plate.

FIG. 9 is a perspective view showing a configuration of a conventional separator plate.

[Explanation of symbols]

1, 2, 39, 40 separator plate, 3, 4 electrode, 5
Electrolyte membrane, 6 unit cells, 10, 11 gas flow path, 24
Oxidant supply port, 25 oxidant discharge port, 26 fuel supply port, 27 fuel discharge port, 28 coolant supply port, 29 coolant discharge port, 33 oxidant flow path, 43 fuel flow path, 53
Coolant flow path.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Koji Hamano 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Norio Mitsuda 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 5H026 AA04 AA06 CC03 CC08

Claims (3)

[Claims] 1. A single cell comprising an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode, and a plurality of fuel flows parallel to each other from a fluid supply port to a fluid discharge port for supplying a fuel fluid to the fuel electrode. A fuel cell comprising a stack in which a passage and a separator plate having a plurality of oxidant flow paths arranged in parallel from a fluid supply port to a fluid discharge port to supply an oxidant fluid to the oxidant electrode are sequentially laminated. At least the plurality of oxidant flow paths are formed of a plurality of groups of parallel flow paths, and the plurality of groups of parallel flow paths each run by folding back a divided region of the main surface of the separator plate. And the fuel cell. 2. A single cell comprising an electrolyte membrane sandwiched between a fuel electrode and an oxidant electrode, and a plurality of fuel flows parallel from a fluid supply port to a fluid discharge port for supplying a fuel fluid to the fuel electrode. A fuel cell comprising a stack in which a passage and a separator plate having a plurality of oxidant flow paths arranged in parallel from a fluid supply port to a fluid discharge port to supply an oxidant fluid to the oxidant electrode are sequentially laminated. At least the plurality of oxidant flow paths are formed of a plurality of groups of parallel flow paths, and each of the plurality of groups of the parallel flow paths at the same distance from each fluid supply port is a main surface of the separator plate. A fuel cell, wherein the fuel cell is disposed in a distributed manner. 3. The separator plate is provided with a plurality of parallel coolant flow paths through which a cooling medium flows, and the plurality of coolant flow paths comprises a plurality of groups of parallel flow paths. 2. The fuel cell according to claim 1, wherein the road runs while turning back an area obtained by projecting the divided area where the oxidant flow path travels on the separator plate. 3.